Red blood cells or Erythrocyte and Anemia

RBC is a circular, biconcave, nonnucleated disc.

Advantages of biconcave disc:

(i) Allows considerable alteration in cell volume. Thus, can withstand consider able changes of osmotic pressure resist hemolysis. and

(ii) Allows easy folding of RBC on itself when it passes through capillaries.

(iii) Haemoglobin remains distributed in the centre of the RBC which facilitates optimal and quick exchange of gases (i.e. oxygen and carbon dioxide).

The mature RBC has no nucleus, no mitochondria and no ribosome, still it can live for 120 days and can carry out its normal activities. How?

RBCS depend entirely on glucose metabolism for its energy supply.Glucose is transported easily across the cell membrane by facilitated diffusion (i.e. carrier mediated passive process). Although the cell has no mito chondria but it has cytoplasmic enzymes for metabolizing glucose and other substances and for utilization of oxygen. As these metabolic systems become progressively less active with time, thus limits the life span of RBC.

STRUCTURE: RBC contains haemoglobin,

which takes pink colour with Leishman's stain. Its cell membrane contain circular pores, which are concerned with ingress or egress of water and electrolytes. Below the cell membrane is a contractile layer of lipo-protein 'spectrin', which is arranged in a fibrillar manner. It maintains the shape and flexibility of RBC membrane and also contains specific blood group substance, the antigen.

COMPOSITION 

(i) 62.5% water

(ii) 35% Haemoglobin (29.5 ± 2.5 pg/RBC) 

(iii) 2.5%:

(a) Sugar - glucose

(b) Lipids - cephalin, cholesterol and lecithin

(c) Protein-Glutathiones, albumin like insoluble protein, acts as a reducing agent, thus prevents damage of haemoglobin.

(d) Enzymes of glycolytic system; carbonic anhydrase and catalase. 

(e) Vitamin derivatives, and

(f) Ions - Na+, K+, Ca²+, PO^3-4 and SO^2-4

 ANAEMIAS 

Anaemia is a condition characterized by reduction in the number of RBCs less than 4 million/cumm or their content of haemo globin less than 12 gm% or both.

Grading

Mild Anaemia : Haemoglobin 8-12 gm%

Moderate Anaemia : Haemoglobin 5-8 gm%

Severe Anaemia : Haemoglobin less than 5 gm%

CLASSIFICATION

1. Haemorrhagic Anaemia due to blood loss

(i) Acute i.e. sudden loss of blood

(ii) Chronic - slow loss of blood due to piles; worms infestation; peptic ulcer; during menstruation etc.

2. Dietary deficiencies due to iron, vitamins etc.

3. Dyshaemopoiesis or abnormal haemo poiesis resulting in aplastic anaemia. 

Causes:

(i) X-rays irradiations

(ii) y-rays irradiation

(iii) hypersensitivity of bone marrow to 

(a) cytotoxic drugs, sulpha drugs etc. 

(b) chemicals.

Dyshaemopoiesis is characterized by decrease in all types of blood cells - RBCs, WBCs and platelets

4. Hemolytic anaemias - anaemias due to excessive destruction of RBCs.

(i) Intrinsic (intra-corpuscular) defects - hereditary in nature: 

(a) Congenital (or familial or heredi tary) spherocytosis.

(b) Haemoglobinopathies - sickle cell anaemia and thalassaemia.

(c) Erythroblastosis foetalis.

(ii) Extrinsic (extra-corpuscular) defects - acquired in nature:

(a) Antigen-antibody reaction.

(b) Infection e.g. malaria.

(c) Drugs/poisons e.g. quinine, aspirin, burns, snake venom etc. 

(d) Hypersplenism, it causes over activity of normal destructive mechanism.